Article comprising and method of placing indicia thereon



Nov. .29, 1949 c. E. BECHARD ARTICLE COMPRISING AND METHOD OF PIJAGING INDIGIA THEREON Filed Feb. 24, 1948 lnven tor" Convad E. Bechard,

His A t frorneg.

Patented Nov. 29, 1949 UNITED STATES PATENT OFFICE ARTICLE COMPRISING AND METHOD OF PLACING INDICIA THEREON Conrad E. Bechard, Euclid, Ohio, assignor to General Electric Company, a corporation of New York 9 Claims.

My invention relates in general to electric lamps, and more particularly to internally coated envelopes or bulbs therefor. Still more particularly, my invention relates to such coated envelopes or bulbs provided with indicia thereon, and to a method of manufacturing the same.

Electric incandescent lamps and similar devices customarily have their glass enclosures or bulbs provided with certain identifying indicia or markings, such as the manufacturers name or trade-mark,the wattage and voltage rating,the type of lamp, and other markings. These identification marks or designs, which are preferably applied to the interior wall of the bulb to prevent their obliteration or marring during the handling and shipment of the lamp, have usually been formed of a suitable ink composition applied to the glass bulb by a stamping operation, such as by a rubber stamp.

It has been found that in lamp bulbs of the type described and claimed in co-pending U. S. application Serial No. 878, Pipkin, filed January 7, 1948, wherein the interior surface of the bulb is provided with a light-diffusing coating of extremely fine silica particles, the presence of such an ink identification mark on the inner wall of the bulb, beneath the coating thereon, adversely affects the strength of the lamp filament for some reason or other, and so foreshortens its normal life. The explanation for this apparently is that, since to produce a satisfactory and legible internal ink identification mark on the internally coated bulb it is necessary to apply the ink marking to the inner wall of the bulb prior to the deposition of the coating thereon, the ink marking is trapped beneath the coating and thus does not become suificiently baked-out, during the customary heating of the bulb during the lamp exhausting operation, to completely drive out and cause evacuation from the bulb of those ingredients of the ink composition which, after sealing of the bulb, form impurities therein which are detrimental to filament life.

It is one object of my invention therefore to provide an internally coated electric lamp envelope having a novel internal identification mark or indicium thereon.

Another object of my invention is to provide an electric lamp having an internally coated envelope containing an electric energy translation element and provided with a novel internal identification mark or indicium thereon.

A further object of my, invention is to provide a novel method of producing a clear and legible identification mark or indicium on the irmer wall of a lamp envelope internally coated with a finelydivided powder material.

Further objects and advantages of my invention will appear from the following description of a species thereof and from the accompanying drawing in which:

Fig. 1 is a perspective view of an electric incandescent lamp provided with an internally coated bulb having an identification mark or indicium thereon according to the invention; Fig. 2 is a plan view of a portion of the inner wall of the bulb of Fig. 1, showing the identification mark thereon; and Figs. 3 and 4 are views illustrating the steps involved in producing an internally coated, internal indicium-bearing electric lamp bulb in accordance with the invention, Fig. 3 showing the application of the coating to the inner wall of the bulb and Fig. 4 showing the formation of the indicium on the coated inner wall of the bulb.

Referring to the drawing, the electric incandescent lamp shown in Fig. 1 comprises a sealed glass envelope or bulb I provided at its neck end withareentrant stem 2 having a seal or press portion 3. An electric energy translation element or filament 4, such as a coiled or coiled coil wire of tungsten or other suitable refractory metal, is mounted within the bulb and connected at its ends to a pair of lead-in wires 5, 6 which are sealed through the press portion 3 of the stem 2 and extend to the terminals of a base "I cemented or otherwise secured to the neck end of the bulb.

The inner wall of the bulb l, which may be either clear or inside frosted, is provided with a lightdiffusing coating 8 of finely-divided mate rial which may be of the type described and claimed in the above-mentioned co-pending Pipkin application Serial No. 878 and comprising extremely fine particles of substantially pure silica deposited on the bulb wall by the combustion of an inflammable silicon compound within the bulb. As disclosed in the said Pipkin application, the coating 8 of silica powder may be produced by impregnating any suitable form of wick with a volatilizable liquid silicon compound such as ethyl silicate, and burning the compound inside the bulb in the presence of a stream of air or oxygen to insure continuing combustion and to carry the products of combustion other than silica out of the bulb.

As illustrated in Fig. 3 of the drawing, the burner or wick may consist of a ball or wad 9 of glass thread wound on the end of a wire rod Ill. The wad is dipped into the ethyl silicate,

3 and the rod is then inserted in a tube II through which a stream of oxygenous gas is blowing. It is preferable to use pure oxygen, rather than air, for example. in order to insure complete combustion and subdivision of the particles of smoke and thereby avoid deposits of flocculent silica. The wad is then lighted and the bulb I is placed over the burning wad and rotated on a hollow tubular chuck I2 which surrounds the tube II and terminates at its upper end in a thin, resiliently compressible collet" portion I3 which grips the bulb. A dense white smoke is emitted consisting of silicon dioxide (1. e. silica), water vapor and carbon dioxide, the silicon dioxide being deposited on the inner surface of the bulb in a smooth adherent film, and the water vapor and carbon dioxide being blown out of the bulb and downward through the interior of the chuck I2. The density of the coating may be controlled either by removing the bulb after a predetermined time or by initially applying to the wad 9 a predetermined amount of the ethyl silicate.

In the apparatus illustrated in Fig. 3, the hollow chuck I2 is rotatably mounted on a bracket I4 and is driven from any suitable source of power through a belt I5 encircling a pulley l6 attached to the chuck. The tube II is adjustably supported by a clamp l1 extending from a suitable base I 8 which also carries the bracket I4. As illustrated, the tube II is preferably adjusted so that the wad 9 is approximately at the center of the spherical portion of the bulb.

In accordance with the invention, the bulb I with the coating 8 on its inner clear or frosted wall, is provided with an internal identification mark or other indicium or design I9 formed by areas of the bulb devoid of the coating material 8. These uncoated areas of the coated inner wall of the bulb I may be produced by a removal of the coating 8 from such bulb wall areas, preferably by means of a stamp 20 of natural or synthetic rubber or other suitable resilient material to which the coating material will readily adhere, which stamp is firmly pressed against the coated inner wall of the bulb, as shown in Fig. 4. Upon withdrawal of the stamp 20 from the bulb wall, the coating material 8 adheres to the symbol or other design-forming characters of the stamp and is thus removed from the bulb wall, leaving welldefined uncoated areas corresponding to the symbols or other design-forming characters of the stamp.

The marking of the bulb in accordance with the invention may be performed in the manner and with the apparatus shown in Fig. 4, which apparatus may be combined with a conventional indexing-type lamp sealing-in and exhausting machine, the bulb-marking apparatus in such case being located to one side of the bulb-sealing turret of the machine and the bulbs being transferred to the said sealing turret after the marking thereof, as shown, for example, in U. S. Patent 1,620,447 to Donovan, dated March 8, 1927. The bulb I is supported or rested, neck end down,

in one of a series of bulb holders 2| carried by a, turret 22. The bulb holder turret 22 is intermittently indexed and positioned, by suitable actuating means (not shown), in such manner as to successively position the bulbs directly over and in register with a vertically reciprocable plunger 23 yieldably carrying at its upper end the rubber stamp 20 having thereon the desired character or design 24 on its upper or impressing surface. When the bulb I is thus positioned over the plunger 23, the latter is moved upwardly by may be effectively accomplished by means brush 26 which is moved laterally across the suitable means (not shown) to press the rubber stamp 20 firmly against the coated inner wall of the bulb. During the period the stamp 20 is thus pressed upwardly against the inner wall of the bulb, the latter is firmly held down in its holder 2|, against upward movement therein, by means of a hold-down stop which may be in the form of a cup 25 shaped to have a circular line or area of contact with and centered around the upper end of the bulb.

To assure the production of uniformly clear and well-defined legible marks or designs I9 on the bulb, it is necessary to periodically clean the rubber stamp 20 of the coating material which adheres thereto and accumulates thereon. This of a impressing surface of the rubber stamp 20 when the latter is in its lower position. The brush 29 is carried by a holder in the form of a slide 21 which is mounted on guide tracks 28 for horizontal reciprocating movement thereon. The brush holder 21 is reciprocated by a pair of swing or lever arms 29 which are pivotally mounted at one end on a stationary part of the sealing-in machine and are pivotally connected at their other ends, by a pin and slot connection, to the brush holder 21. The arms 29 are swung or oscillated by suitable actuating means (not shown) to reciprocate the brush holder 29 on its guide tracks 28 and so move the brush 28 across the upper or impressing surface of the rubber stamp 20 to clean the same of coating material. While it is preferable to clean the stamp 20 of coating material after each bulb-marking operation in order to obtain the clearest and most welldefined mark possible, such cleaning operation may be performed instead after a given number of bulb-marking operations, for instance, after every other or after every third or fourth, etc. marking operation, the number of marking operations permissible before cleaning of the stamp is required depending in each case on the thickness and the type of coating material 8 on the bulb.

While I have described the invention as applied to an electric incandescent lamp bulb provided with a light-diffusing coating of the type described and claimed in the previously men tioned co-pending Pipkin application Serial No. 878, it will be obvious that it may be applied equally as well to envelopes or bulbs for other types of electric lamps or devices, or provided with other types of internal coatings, for instance, to fluorescent lamps of the type in general use at present having a coating of fluorescent powder on the inner wall of the lamp envelope. The only requirements are that the powder coating material 8 on the bulb be of suflicient particle fineness to readily adhere to the stamp 20 when pressed against and withdrawn from the coating, and that the thickness of the coating material be thin enough to cause removal of substantially the full thickness of the coating material from the bulb wall so as to produce a well-defined and legible mark or design on the bulb when viewed from the exterior.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric lamp comprising a sealed glass envelope having a coating of finely-divided material on its inner surface and identifying indicia on said envelope defined by portions of the envelope free of said coating.

2. An electric lamp comprising a sealed glass envelope the inner surface of which is coated with a finely-divided material except for certain selected areas thereof constituting identifying indicia.

3. An electric lamp comprising a sealed glass envelope having a coating of finely-divided material on its inner surface, and identifying indicia on said envelope constituted by a grouping of symbol-delineating voids in said coating.

4. An electric lamp envelope having a coating of finely-divided material on its inner surface and provided with internal identifying indicia thereon constituted by portions of the envelope free of said coating.

5. An electric incandescent lamp comprising a sealed glass envelope having a coating of fine silica powder on its inner surface, a filament within said envelope, and identifying indicia on said envelope defined by portions of said envelope free of said coating.

6. The method of manufacturing inside indlcia-bearing llght-difiusing envelopes for electric lamps which comprises, depositing a coating of finely-divided material on the inner surface of the envelope, and removing the said coating 2 from certain selected areas of the envelope to define identifying indicia thereon.

'l. The method of manufacturing inside indicia-bearing light-diflfusing envelopes for eiec-' tric lamps which comprises, depositing a coating 30 5 stamp,

of finely-divided material on the inner surface of the envelope, and pressing a yieldable designforming stamp against the coated inner wall of the envelope to remove the said coating from areas of the envelope wall corresponding to the design characters on the stamp and thus form identifying indicia on the envelope.

t, The method of manufacturing inside indicia-bearing light-diifusing envelopes for electric lamps which comprises burning a volatile silicon compound within the envelope to form a fume of silica and collecting solid particles of the silica on the inner surface of the envelope, and. then removing the said coating from selected areas of the envelope to define identifying indicia thereon.

9. The method of forming identifying indicia on the inner walls of lamp envelopes having a coating of finely-divided material on their inner surface, which method comprises pressing a yieldable design-forming stamp against the coated inner wall of the envelope to remove the said coating from areas of the envelope wall corresponding to the design characters on the and periodically cleaning the impression surface of the stamp of the coating material which accumulates thereon.

CONRAD E. BECHARD.

No references cited. 

